Clare Island Survey — Trec-Grotvt/i. Q 17 



sap-wood, exact records are difficult to obtain. Stumps in marsh peat are, on 

 the whole, larger, and show a more rapid growth than those in mountain 

 peat, and the character of the underlying soil has evidently influenced their 

 growth considerably. 



The Present Treeless Condition of the West Coast of Ireland, 

 and its Probable Causes. 



If Clare Island alone gave evidence of a former wooded condition which 

 no longer prevails, it might be assumed that special influences have been 

 operating upon that area, which would account for the disappearance of trees. 

 The effect of cultivation and grazing upon a limited area for a long period 

 would be quite sufficient to prevent natural regeneration taking place, and 

 bring about existing conditions. But a review of the coast-line between 

 Donegal and Kerry, and of the various islands lying in the Atlantic, reveals 

 not merely a general absence of trees over wide stretches of country, but, what 

 is of greater significance, the occurrence of tree, shrub, and shade species in the 

 form of small detached colonies a few miles apart, strongly suggestive of a 

 former wooded condition of the intervening spaces. The presence of tree- 

 stumps and logs in and under the peat which covers so large a proportion of the 

 land-surface bears out this theory, although the peat remains probably belong 

 to an older period than that of the existing forest flora. Where patches of 

 natural woodland occur which prove the possibility of forest-growth under 

 existing conditions, they are found to consist of small Oak, Ash, Hazel, Holly, 

 Birch, Mountain Ash, with an occasional Elm, Aspen, Juniper, or Yew. The 

 general composition of this forest flora differs little, if at all, from that 

 prevailing over three-fourths of the British Isles ; and, with the exception of 

 Birch, Juniper, Aspen, and Mountain Ash, these species, but more especially 

 Oak and Hazel, are associated with better soils and warmer summers than 

 those now existing in the west of Ireland generally. The condition of these 

 scattered woods is one which suggests the last stage of debility and degrada- 

 tion, the stems being short, crooked, and moss-grown, while the rate of 

 growth is so slow that little alteration in the size of the trees or condition of 

 the woods can be noted over long periods. It is quite evident that they form 

 the rearguard of a retreating forest-growth, rather than the outposts of an 

 advancing one, and the general conclusion to which a careful observer must 

 arrive from all the facts before him is that a broad-leaved forest, in which Oak 

 and Hazel predominated, invaded the whole of the west of Ireland at some 

 early period, flourished there for an unknown number of centuries, and is 

 now in full retreat. 



B.I. A. proc, vol. xxxi. C 9 



